Using Smaller-Sized Filters with Baader’s Universal Filter Changer (UFC) (Part 8)

Smaller-Sized Filters with Baader UFC-System :

We've been asked a few times recently on how to set up the Baader UFC for use with a DSLR and a range of wide-field imaging refracting telescopes. So we thought we would write a short blog on some ways this can be done.

Let us start from the telescope side first.

All the enquiries we have had, the wide field refractors have 2" barrel focusers, so there is our starting point. The telescope side of the UFC Base (to which everything else in the UFC system is connected to) uses Baader's S70 dovetail adaptors to allow the UFC to fit to telescopes.

Looking at the UFC main diagram above Baader do a Baader UFC S70 / 2" SC-thread (f) Telescope-Adapter (optical height: 1 mm) (#2459128 , € 25,-) that allows 2"/SC male-thread accessories to be used. More about our UFC Telescope Adapters can be found in our blog: The UFC telescope-side adaptors.

 Baader UFC D 50.4 Filterschieber # 2459113

Baader UFC D 50.4 Filter Slider (#2459113 , € 45,-)

It may appear, at first glance, that the Baader Planetarium Universal Filter Changer (UFC) is for use with larger 2″/50mm sized filters. Not so! You can use popular, and more often used smaller 1.25″, 31mm unmounted or 36mm unmounted filters too. So how can the filter slider drawer made for use with larger sized filters be used with smaller filters? Simple – with a step-down adaptor. Baader call these step-down adaptors AUX Filter Holders.

Apart from the UFC Base, and the associated telescope- and camera-side adaptors for your telescope/camera combination, you will need Baader UFC D 50.4 Filter Slider (#2459113 , € 45,-) . It is to this particular filter slider that any of the AUX step-down adaptors attach to.

We offer three AUX step-down filter holder adaptors for use with the D50.4mm slider:

1.25″ UFC Aux Filter Holder (left) and inserted into the D50.4 Slider.

1.25″ UFC Aux Filter Holder (left) and inserted into the D50.4 Slider.



31mm/36mm Unmounted UFC Aux Filter Holder and inserted into the D50.4mm Slider

31mm/36mm Unmounted UFC Aux Filter Holder and inserted into the D50.4mm Slider


The 31mm and 36mm unmounted AUX holder have a small narrow “shoulder” on the inside of the unit to support of the filter once the filter is in place (otherwise the filter would drop or fall straight through the holder!).

The AUX filter holder is simply inserted into the UFC filter slider's circular opening and then it is secured in place using the three Allen key hex-screws that come with the filter slider. As with the 31/36mm AUX filter holder, the D50.4mm slider also features a small “shoulder” in the “base” of the filter opening to support the AUX holder in place (as well as to support 50.4mm unmounted filters when the AUX holder is not used).

The 1.25″/31mm/36mm filters can be inserted, removed or exchanged with the AUX holder either in place or with it removed from the UFC filter slider – its personal preference.


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About the author: Lee Sproats

Lee Sproats

Dr. Lee Sproats has been interested in astronomy since watching Star Wars in 1977 and has appeared on the UK Sky at Night TV programme. He then went on to study Astronomy where he obtained a degree and then a PhD in the subject at University College London/Mullard Space Science Laboratory. He has worked in Australia in radio astronomy and used optical/infrared telescopes on Hawaii and La Palma and Lowell and Kitt Peak observatories in the USA. After working for the University of Surrey to promote the use of computers for teaching in UK higher education and then as an IT trainer for a stock market company, he went on to work for Greenwich Observatory Ltd where he ran their northern branch and then worked for David Hinds Ltd dealing with our and Celestron products. He is often involved in flight excursions that take passengers to observe the northern lights, has led trips to see the great USA 2017 eclipse near Hopkinsville and was lead astronomer onboard a specially chartered 737 to view the 2015 total solar eclipse at 38,000ft. Lee`s astronomical interests include Lunar observing, astrophotography, photometry and pro-am collaborations.

Since David Hinds stopped operation in December 2020, Dr. Sproats works for Baader Planetarium as our UK representative/consultant and is responsible for looking after our UK/Eire dealers, dealing with Baader Planetarium/PlaneWave/10Micron product support, writing articles and also is involved in our large telescope and observatory instrumentation projects.

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